In the conventional four cycle, reciprocating, internal combustion engine, particularly on automotive vehicles, the engine typically is operating under substantially no load or light load much of the time. During such no load or light load conditions only a relatively small engine displacement is needed. It is only when the engine is under heavy load that higher engine displacement is required, such as when starting or accelerating the vehicle. However, these heavy load conditions dictate the engine displacement even when light load conditions are involved because the engine must have the capacity to handle the heavy load conditions satisfactorily.
Thus, there has existed the problem of improving the efficiency of such engines by automatically varying the engine displacement in accordance with the load on the engine, with the engine displacement being minimized under no load conditions and greatly increased under high load conditions.
U.S. Pat. No. 2,372,472 to Campbell discloses an internal combustion engine which is superficially similar to the present invention in that it provides a coil spring under compression between each engine piston and the engine crankshaft. The purpose of this arrangement, as explained in the Campbell patent, was to enable the piston to travel farther on the exhaust stroke than on the compression stroke. A portion of the initial power of the explosion in the cylinder is said to be stored in and then released by this spring to the crankshaft. Also, the longer exhaust stroke is said to exhaust from the cylinder a larger percentage of the spent gases. However, the Campbell patent does not address itself to the problem of varying the engine displacement in accordance with the actual load on the engine.